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University of Utah designs self-focusing spectacle lenses

USTAR

(Healio.com) – Researchers at the University of Utah created a compact tunable-focus liquid lens suitable for adaptive, smart eyeglass application.

“Most people who get reading glasses have to put them on and take them off all the time,” Carlos Mastrangelo, University of Utah electrical and computer engineering professor, said in a press release from the school. “You don’t have to do that anymore. You put these on, and it’s always clear.”

The university’s research was published in Optics Express.
created eyeglass lenses made of glycerin, a thick colorless liquid enclosed by flexible rubber-like membranes in the front and back.

The rear membrane in each lens is connected to a series of three mechanical actuators that push the membrane back and forth like a transparent piston, changing the curvature of the liquid lens and, therefore, the focal length between the lens and the eye, according to the release.

The lens has an aperture diameter of 32 mm, optical power range of 5.6 D and electrical power consumption less than 20 mW. The lens, inclusive of its piezoelectric actuation mechanism, is 8.4 mm thick and weighs 14.4 g. The measured lens RMS wavefront aberration error was between 0.73 µm and 0.956 µm, according to the study.

The lenses are placed in special eyeglass frames also invented by Mastrangelo, who is a professor for USTAR, the Utah Science Technology and Research economic development initiative, and other members of the research group, with electronics and a battery to control and power the actuators.

In the bridge of the glasses is a distance meter that measures the distance from the glasses to an object via pulses of infrared light.

When the wearer looks at an object, the meter instantly measures the distance and tells the actuators how to curve the lenses. If the user then sees another object that is closer, the distance meter readjusts and tells the actuators to reshape the lens for farsightedness, according to the release. The lenses can change focus from one object to another in 14 milliseconds.

A rechargeable battery in the frames could last more than 24 hours per charge, according to Mastrangelo.

The project was funded with a grant from the National Institutes of Health and the National Institute of Biomedical Imaging and Bioengineering.